CMP Warning

**Aguila Blanca** · April 20, 2021, 05:10 PM

I received TWO e-mails today from the CMP. Both forwarded a warning about using hot or heavy loads in M1s and 1903 rifles. Most of you probably already are aware of this, but I'm posting it as a general advisory.

Nathan · April 20, 2021, 09:16 PM

Why today of all days did we get this red alert?

**Aguila Blanca** · April 20, 2021, 11:35 PM

Beats me, but they sent one e-mail in the morning and another later in the day, so somebody at the CMP HQ must think we need to know this.

Pathfinder45 · April 20, 2021, 11:56 PM

Contrary to what the warning says, I have always been under the impression that the 1903 Springfield was designed for a cartridge with a 220 grain bullet.

mehavey · April 21, 2021, 06:04 AM

Someone may be having a problem with sentence construction.

It's an AND condition:

- Loaded beyond 50,000 CUP*
~~ AND ~~
- Has a bullet weight more than 172-174gr

*SIDENOTE: SAAMI specifies
50,000 CUP <--> 60,000 psi

But I'm always wiliing to be shown the error of my ways.....

Nathan · April 21, 2021, 06:58 AM

What is the impact of bullet weight? I can understand pressure.

JustJake · April 21, 2021, 08:47 AM

I know guys who hunt hogs with their Garands. They use 180gn or 220gn 30-06 hog-slammin' loads.

Zero issues ... and a lot of DRT hogs. Why? Because all factory '06 ammo is loaded below the 50,000 CUP pressure limit. Bullet-weight is irrelevant.

Heck, the .308 Win cartridge has a 52K CUP limit. Guess how many Garands are out there running .308 barrels, like the old Navy Garands. In fact, many of the more recent .308 M1s in circulation were built and sold by the CMP themselves using modern Criterion barrels.

Plus, IIRC, 7.62mm surplus ammo, which a .308 M1 can also shoot, is actually CUP-rated below .308 Win, like a 50K max, I believe.

Do you think the CMP honchos will be issuing a "recall" on any .308 Garands they sold because the cartridge they're chambered for has a 52K max pressure limit?

If you're still goosey about shooting heavier-than-172gn bullets in your M1, just remove the GI gas plug and install one of the adjustable gas plugs on the market. Get out to the range, tune in your load of choice by dialing-in that internal screw in the plug.

Problem (or non-problem) solved. Easy-peasy.

You can thank me later.

Jim Watson · April 21, 2021, 09:40 AM

It is not the bullet weight or the chamber pressure that is concerning.
It is the port pressure. A full charge load of slow burning powder - like you would tend to pick for top performance with a heavy bullet - will give greater than design port pressure and can bend the hard to replace operating rod.

Bart B. · April 21, 2021, 09:51 AM

The USAF developed and USN load for 7.62 Garands at 600 yards to 1000 was 44 grains of IMR4320 under Sierra' 190's in new M118 match cases.

Commercial 30-06 match ammo for Garands often used 180 grain bullets.

Jim Watson · April 21, 2021, 01:24 PM

They probably knew what size gas port to drill and they had spare parts if they beat up the guns.

**44 AMP** · April 22, 2021, 03:58 PM

Quote:

I have always been under the impression that the 1903 Springfield was designed for a cartridge with a 220 grain bullet.

It was. It was designed to use the .30-03 round which was originally loaded with the 220gr bullet used in the .30-40 Krag.

When the 30-06 replaced the .30-03 and used a lighter bullet, there was no change to the actions, just the barrels.

Red Devil · May 4, 2021, 09:18 AM

Quote:

Originally Posted by Jim Watson

It is not the bullet weight or the chamber pressure that is concerning.
It is the port pressure. A full charge load of slow burning powder - like you would tend to pick for top performance with a heavy bullet - will give greater than design port pressure and can bend the hard to replace operating rod.

Exactly so.

Port Pressure - is the only issue.

Red

**44 AMP** · May 4, 2021, 03:45 PM

The "warning" is not in any way new "news". I think its just somebody at the CMP doing an extra layer of CYA.

HiBC · May 4, 2021, 04:12 PM

It might be some hog hunter shooting 220 gr loads using full case 4831 loads bent his op rod and then whined to CMP they sold him a gun that was defective.

I don't know for sure,but it might be that a Navy Shooting team has armorers ,tuners,testers,and bins of parts to develop winning combinations that work.

Most folks don't have those resources. I'm figuring on my op rod lasting longer than I do.

There are hollowed out gas cylinder lock screws and adjustable ones. Both can be a remedy. So far,I've used H-4895 and 168 gr BTHPs . I'm not pushing anything. I'm not going to worry about it.

Its also true that the modern crop of 1903/1903A3/ 1903A4 rifles that people are shooting at CMP games are resurrected previously de-activated drill rifles. CMP knows that.
I built a 1903A4gery on one. It shoots fine. I don't think I'll try to push it too hard.

Gamers always push whatever limits they can . It might be the CMP just wants to keep things safe and have a prudent paper trail.

JustJake · May 4, 2021, 09:06 PM

Quote:

Gamers always push whatever limits they can . It might be the CMP just wants to keep things safe and have a prudent paper trail.

A couple of 1903s shot at the CMP Talladegha old-school matches have imploded from idiots using hot-rodded .30-06 reloads.

That said, Shuff's Parkerizing builds 16" Mini-Gs (M1 Garands chopped to "carbine" length) in .35 Whelen.

He installs an adjustable gas plug to tune the action to cycle reliably while protecting the op rod and gas system from excessive pounding from the Whelen rounds. It's the Schuster Mfg. plug, I think.

Prof Young · May 5, 2021, 09:32 AM

Exact same warning that came with my recently arrived Garand.

Life is good
Prof Young

Don Fischer · May 5, 2021, 09:51 AM

Now they tell us. Been loading my 1903 with 180gr bullet's since I got it in 1995. also no clue on pressure, let pressure signs guide me. Seem's to me the original 30-06 load was a 220gr bullet later changed to a 150gr.

Red Devil · May 5, 2021, 11:38 AM

Quote:

Originally Posted by JustJake

A couple of 1903s shot at the CMP Talladegha old-school matches have imploded from idiots using hot-rodded .30-06 reloads...

WARNING ON “LOW-NUMBER” M1903 SPRINGFIELDS (CMP)

To sweep Dbl. heat treated "High-Number" 03's and 03-A3's into this bin...?

... is Lawyerly.

No way even a "hot-rod" handload is going to exceed a proof load, unless one is, well, insane.

Red

**44 AMP** · May 5, 2021, 12:05 PM

Quote:

Originally Posted by JustJake View Post
A couple of 1903s shot at the CMP Talladegha old-school matches have imploded from idiots using hot-rodded .30-06 reloads...

Wow, that must have been really something! How did they get them to implode???

April 20, 2021, 11:35 PM	#3
Aguila Blanca Staff Join Date: September 25, 2008 Location: CONUS Posts: 18,466	Beats me, but they sent one e-mail in the morning and another later in the day, so somebody at the CMP HQ must think we need to know this. __________________ NRA Life Member / Certified Instructor NRA Chief RSO / CMP RSO 1911 Certified Armorer Jeepaholic

April 21, 2021, 08:47 AM	#7
JustJake Senior Member Join Date: August 12, 2020 Posts: 497	I know guys who hunt hogs with their Garands. They use 180gn or 220gn 30-06 hog-slammin' loads. Zero issues ... and a lot of DRT hogs. Why? Because all factory '06 ammo is loaded below the 50,000 CUP pressure limit. Bullet-weight is irrelevant. Heck, the .308 Win cartridge has a 52K CUP limit. Guess how many Garands are out there running .308 barrels, like the old Navy Garands. In fact, many of the more recent .308 M1s in circulation were built and sold by the CMP themselves using modern Criterion barrels. Plus, IIRC, 7.62mm surplus ammo, which a .308 M1 can also shoot, is actually CUP-rated below .308 Win, like a 50K max, I believe. Do you think the CMP honchos will be issuing a "recall" on any .308 Garands they sold because the cartridge they're chambered for has a 52K max pressure limit? If you're still goosey about shooting heavier-than-172gn bullets in your M1, just remove the GI gas plug and install one of the adjustable gas plugs on the market. Get out to the range, tune in your load of choice by dialing-in that internal screw in the plug. Problem (or non-problem) solved. Easy-peasy. You can thank me later. __________________ I use the Jake Brake every chance I get. Don't care if it annoys you. Hear me now?!

May 4, 2021, 03:45 PM	#13
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,832	The "warning" is not in any way new "news". I think its just somebody at the CMP doing an extra layer of CYA. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

May 4, 2021, 04:12 PM	#14
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,286	It might be some hog hunter shooting 220 gr loads using full case 4831 loads bent his op rod and then whined to CMP they sold him a gun that was defective. I don't know for sure,but it might be that a Navy Shooting team has armorers ,tuners,testers,and bins of parts to develop winning combinations that work. Most folks don't have those resources. I'm figuring on my op rod lasting longer than I do. There are hollowed out gas cylinder lock screws and adjustable ones. Both can be a remedy. So far,I've used H-4895 and 168 gr BTHPs . I'm not pushing anything. I'm not going to worry about it. Its also true that the modern crop of 1903/1903A3/ 1903A4 rifles that people are shooting at CMP games are resurrected previously de-activated drill rifles. CMP knows that. I built a 1903A4gery on one. It shoots fine. I don't think I'll try to push it too hard. Gamers always push whatever limits they can . It might be the CMP just wants to keep things safe and have a prudent paper trail. Last edited by HiBC; May 4, 2021 at 04:28 PM.

May 5, 2021, 09:32 AM	#16
Prof Young Senior Member Join Date: August 21, 2007 Location: Illinois - down state Posts: 2,404	Same warning . . . Exact same warning that came with my recently arrived Garand. Life is good Prof Young

April 20, 2021, 09:16 PM	#2
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,331	Why today of all days did we get this red alert?

April 20, 2021, 11:56 PM	#4
Pathfinder45 Senior Member Join Date: January 7, 2008 Posts: 3,224	Contrary to what the warning says, I have always been under the impression that the 1903 Springfield was designed for a cartridge with a 220 grain bullet.

April 21, 2021, 06:04 AM	#5
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,894	Someone may be having a problem with sentence construction. It's an AND condition: - Loaded beyond 50,000 CUP* ~~ AND ~~ - Has a bullet weight more than 172-174gr *SIDENOTE: SAAMI specifies 50,000 CUP <--> 60,000 psi But I'm always wiliing to be shown the error of my ways.....

April 21, 2021, 06:58 AM	#6
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,331	What is the impact of bullet weight? I can understand pressure.

April 21, 2021, 09:40 AM	#8
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,541	It is not the bullet weight or the chamber pressure that is concerning. It is the port pressure. A full charge load of slow burning powder - like you would tend to pick for top performance with a heavy bullet - will give greater than design port pressure and can bend the hard to replace operating rod.

April 21, 2021, 09:51 AM	#9
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	The USAF developed and USN load for 7.62 Garands at 600 yards to 1000 was 44 grains of IMR4320 under Sierra' 190's in new M118 match cases. Commercial 30-06 match ammo for Garands often used 180 grain bullets.

April 21, 2021, 01:24 PM	#10
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,541	They probably knew what size gas port to drill and they had spare parts if they beat up the guns.

May 5, 2021, 09:51 AM	#17
Don Fischer Senior Member Join Date: March 2, 2017 Posts: 1,868	Now they tell us. Been loading my 1903 with 180gr bullet's since I got it in 1995. also no clue on pressure, let pressure signs guide me. Seem's to me the original 30-06 load was a 220gr bullet later changed to a 150gr.